Blade, structural components of a blade, and method for manufacturing a blade and the structural components of a blade

ABSTRACT

A blade, in which at least the composite base structure of the blade is manufactured in a pultrusion process by pulling fibres through at least an impregnation stage and a curing stage, the base structure is equipped with at least one wear area and the said blade is detached from a blade blank formed of a base structure and a wear area. The wear area of the blade is formed of an edge-structure part protruding outside the edge of the base structure.

This application is a Divisional of co-pending application Ser. No.11/992,679 filed on Jun. 2, 2008 and for which priority is claimed under35 U.S.C. §120. application Ser. No. 11/992,679 is the national phase ofPCT International Application No. PCT/FI2006/050410 filed on Sep. 26,2006 under 35 U.S.C. §371 and which claims priority under 35 U.S.C. 119on Finnish Patent Application No. 20055519 filed on Sep. 28, 2005. Theentire contents of each of the above-identified applications are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a method for manufacturing a blade, inwhich at least the composite base structure of the blade is manufacturedin a pultrusion process by pulling fibres through at least animpregnation stage and a curing stage, the base structure is equippedwith at least one wear area, and the said blade is detached from a bladeblank formed of a base structure and a wear area.

In addition, the invention also concerns a blade manufactured accordingto the method, structural components of a blade, and their manufacturingmethods.

Nowadays, composite blades are used in, for example, in doctors of papermachines. The base materials of the blades can be, such as, for example,a polymer material, such as a thermoset or a thermoplastic. One or morefibre reinforcements may have been added to the polymer structure, suchas, for example, carbon, glass, and/or boron fibres and/or othercontinuous fibres, such as, for example, metal fibres. The orientationof such fibres can be used to give elongated blades excellent strengthand stiffness. The fibres are bound to a polymer matrix, so thattogether they form a plate-like and rigid composite structure.

One advantage of composite blades is that they combine lightness withgood strength and a gentle effect on the roll surface being doctored,without this detracting, however, from their doctoring power.

Finnish patent FI-101637 (PCT publication WO-99/12726 A1) discloses oneform of the prior art relating to composite blades. It presents a doctorblade manufactured using a pultrusion method, in which grindingparticles are combined with the fibre reinforcement. These are used toachieve a cleaning and servicing effect on the object being doctored.The servicing layer, in which the grinding particles are incorporated,can be formed by bringing it into contact with carbon fibres, forexample, by impregnating a carbon-fibre fabric with a matrix agent. Thegrinding particles can be along at least one edge of the blade, whichthen forms the wear area, the ‘work edge’ of the blade.

Another form of the prior art is disclosed in Finnish patent applicationFI-981312 (PCT publication WO-99/64674 A1). In it, the blade is alsomanufactured from a composite material, for example in a pultrusionprocess, while the surface of the wear area is given a ceramic coating.The ceramic is attached by an anchor structure to the surface of thecomposite. The anchor structure is attached throughout to the composite.A ceramic coating is manufactured to the surface of the composite, forexample, with the aid of thermal spraying or some other suitableprocess. The process of making the coating takes place essentiallyseparately from the actual pultrusion process. This complicates theproduction of blades.

A third example of composite blades is disclosed in U.S. Pat. No.4,549,933.

At present, blades structures like those described are pulled throughthe pultrusion process, for example, with the aid of glass-fibrereinforcements which are cast into the base structure of the blade inthe pultrusion process. Arranging reinforcements purely for the purposeof pulling increases the manufacturing costs of a blade. In addition,the working tolerance of the blade remains quite limited, as thegrinding particles are bound to the base structure of the blade i.e., tothe carbon-fibre composite, which wears easily, or because the thicknessof the ceramic coating anchored to the composite is otherwise limited.

SUMMARY OF THE INVENTION

The present invention is intended to create a method for manufacturing acomposite blade, a blade made according to a corresponding method, thestructural components of a corresponding blade, and methods formanufacturing the structural components.

According to a first embodiment, in the manufacturing method accordingto the invention, when the blade blank is formed, an edge-structurepart, which forms its own separate piece relative to the base structure,is attached to the composite base structure of the blade. Thisedge-structure part protruding clearly from the edge of the basestructure at right angles relative to the longitudinal axis of the bladei.e., in the transverse direction of the blade, can form in a readyblade, detached from the blade blank, at least one of the wear areasbeing in the blade.

According to one preferred embodiment, the fibres, or in general theblade blank can be pulled through the pultrusion process by anedge-structure part protruding from the base structure, if the edgestructure part is attached to the base structure already during thepultrusion process itself. Thus the edge-structure parts protrudingoutside the edges of the composite part can be protrudingly cast intothe base structure of the blade, even on both sides of it. Owing to thisthe need for special pulling fibres to be cast into the composite willeliminates, from which a blade blank formed in a process is pulledthrough the pultrusion process according to the prior art. Pulling bythe edge strips will also improve the stability of the orientation ofthe fibres.

Another way to make a blade according to the invention is to attach theedge-structure part afterwards to the base structure of a blade that hasbeen made in a pultrusion process. In any event, in both manufacturingmethods is formed a blade, in which the edge-structure part is cast intothe base structure, thus forming a reinforced-plastic structure.

A two-sided edge-structure part attached to a base structure alsopermits surprisingly versatile use for the blade. The same blade can nowbe used even twice. Thus the blade can be reversed, once the weartolerance of one edge has been used up. On the other hand, during themanufacture of the blade, the blade blank can also be split in two alongthe direction of its longitudinal axis. This will give two blades, withtwo different types of wear edge, from a single piece of appropriatelydimensioned blank. One of the blade's working edges will then beequipped with a special edge-part structure while the other edge will beof the composite base material. Thus the same blade can even be used indifferent doctoring positions, once the wear tolerance of one edge hasended.

According to one embodiment, special bonds can be arranged in theedge-structure part. These can be used to ensure the adhesion of theedge-structure part cast to the base structure and protruding outsideits edge, in the base structure of the blade itself. According to oneembodiment, the bonds can be made such that the impregnating agent canpenetrate through the edge-structure part at points corresponding to thebonds. Using such a three-dimensional bond will securely attach the edgestructure to the actual base structure and improve the casting effect.The bonds can also be grouped so as to create a sufficient bond strengthin all directions. This can also help to influence the nature of theindividual bonds relative to each other in the bond group they form.

Other characteristic features of the invention will become apparent fromthe accompanying Claims while further other advantages achieved by theinvention are referred to in the description portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, which is in no way restricted to the embodimentsdescribed in the following, is examined in greater detail with referenceto the accompanying drawings, in which

FIG. 1 shows a rough schematic diagram of one example of themanufacturing method according to the invention,

FIGS. 2 a and 2 b show a blade manufactured according to the invention,as an example of an application, seen from different directions,

FIG. 3 shows another example of the bonds in the edge strip,

FIG. 4 shows another example of a composite base structure, formanufacturing a blade according to the invention,

FIG. 5 shows a third example of a composite base structure, formanufacturing a blade according to the invention and

FIGS. 6 a and 6 b show some additional examples of the arrangement ofbonds in the edge strip and the base structure.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows one example of the method according to the invention, formanufacturing a composite blade 10. The blade 10 according to theinvention is made at least partly using pultrusion technology, in aprocess 20 that is also known as die pultrusion. As such, to one versedin the art, pultrusion 20 is a conventional technique, so that there isno need in this connection to depict it in particularly great detail.

However, in the pultrusion process 20, fibres/a fibre mat 11 is pulledthrough the basic stages characteristic of the pultrusion method,resulting in a blade blank 22, which is either straight or can be reeledonto a reel 27, from which blades 10 can be detached. The fibres 11 canbe, for example, carbon fibre and/or glass fibres and/or aramid fibresand/or boron fibres, this being in no way limited by the basic idea ofthe invention. Examples of the ratios forming a composite consisting of,for example carbon fibre and glass fibre, are 40/60 and even moregenerally 35/65. The composite can have arbitrary fibre orientation.According to one embodiment, the glass-fibre layers can be oriented, forexample, parallel to the longitudinal axis of the blade 10, while atleast some of the layers containing carbon fibre can deviate from thedirection of the longitudinal axis of the blade 10.

The blade blank 22 consists of a rigid shape-profile base structure 15with several fibre layers in the form of a reinforced-plastic structure,which is equipped with at least one wear area 16.1, 16.2. In FIG. 1 thepulling direction of the blank 22 is shown by an arrow. Of the stages ofthe process 20, in this connection reference can be made to at least animpregnation stage 12 and curing stage 14.

The fibres 11 can be arranged in a preset battery of several reels 21.From there, guides (not shown) are used to lead them first of all to theimpregnation stage 12. There, the fibres 11 are impregnated with anexcess of some selected matrix agent 23, such as, for example, a polymermaterial. Examples of these can be said fluoridized thermoset,thermoplastic, or (epoxy) resin. Reference can also be made to resinwith additives, in which the resin can be, for example, filled withnanoparticles. Impregnation is carried out to an excess, the excessflowing off already during the impregnation stage 12. Impregnation 12 isfollowed by the actual die pultrusion, i.e. the curing stage 14.

In pultrusion 14, the fibres 11 impregnated with polymer 23 are pulledthrough a die 14′ of a chosen kind. A set temperature and pressureeffect is also associated with pultrusion 14. As a result of these, thepolymer 23 hardens and gains strength, while the fibres 11 stiffen intothe desired shape defined by the die 14′. The curing stage 14 is achemical reaction of a kind that is, as such, known to one versed in theart, which can be created in zones with differing temperatures/pressureeffects, the arranging of which will be obvious to one versed in theart. Final curing can also be performed as post-curing, for example, ina post-curing autoclave (not shown).

The finished blade blank 22, which is, for example, reeled on a reel 27or is straight, is pulled using pulling means 19. The pulling means 19can consist of, for example, a nip consisting of at least two rollers,through which the blade blank 22 travels to the reel 27. In the case ofthe narrowest type of blade, 100-150 metres of blade blank 22, forexample, can be reeled on the reel 27, after which it can be changed.Finished blades 10 can be detached from the blank 22, for example, bycutting them to the customer size in a later stage, or alternativelyalso instead of reeling. The process described above can be varied inmany different ways.

In the manufacturing process 20 according to the invention, at least oneof the wear areas of the blade 10 is formed from an independentedge-structure part 16.1, 16.2, which in this case is attached to thecomposite base structure 15 already during the pultrusion process 20.The result of the process 20 is a surprising sheet-laminate hybridblade, in which, in the same continuous pultrusion process 20, aresimultaneously formed both the composite base structure 15 and theedge-structure part 16.1, 16.2 intended to wear that is integrated, forexample by lamination, and that is protruding outside the edge of theactual base structure 15. The edge-structure part 16.1, 16.2, or atleast its point 16.1′, 16.2′ can be equipped with a wear-resistanttreatment, or a coating, which can be implemented, for example, usingmethods according to the prior art. A surprising feature of this it maynot be necessary to further process the blade blank 22 obtained as aresult of the pultrusion process 20 in order to create specialwear-resistant areas, but instead these can be already in the edge strip16.1, 16.2 itself, which is attached to the composite 15 by casting.This is an obvious advantage of the manufacturing technique.

In the embodiment according to FIG. 1, an edge strip 16.1, 16.2 isattached to both sides of the base structure 15 in the pultrusionprocess 20. The strips 16.1, 16.2 are introduced to the process flowfrom coils 16′. Depending on the material of the strips 16.1, 16.2, theycan also be impregnated with a polymer material 23. This appliedespecially in the case of a composite strip. Before the actual curingstage 14, the strips 16.1, 16.2 are positioned from the entry side 26 ofthe die 14′ relative to the fibres 11, in such a way that they becomeintegrated with the fibre-reinforced composite 15 to form a singleentire blade blank 27 and form a structure protruding outside the edgeof the composite 15 in the lateral direction of the composite. In otherwords, edge strips 16.1, 16.2, possibly treated with a polymer material23, as well as fibres 11 impregnated with a polymer material 23 are bothfed into the die 14′, in which die 14′ the strips 16.1, 16.2 are thencast, over part of their width and over their entire length, onto thecomposite base structure 15, for example, to both of its edges. Thecasting is performed in the die 14′, in which space is available for thestrips 16.1, 16.2.

The attachment of edge strips 16.1, 16.2 on both sides relative to theactual composite base structure 15 achieves a surprising advantage interms of manufacturing technique, that the blade blank 22, i.e., inpractice the polymer-impregnated fibres 11, can be pulled through thepultrusion process 20 by these edge-structure parts 16.1, 16.2protruding outside it in the lateral direction of the base structure 15.Pulling performed using the strips 16.1, 16.2 improves the stability ofthe orientation of the fibres. Strip pulling eliminates the need foractual pulling fibres/strings. On the other hand, pulling fibres too,integrated with the composite 15 or the strip 16.1, 16.2, can still beused if so desired. The pulling strings can then, for example, bearranged in the working tip 16.1′, 16.2′ of the strip 16.1, 16.2, wherethe wear-resistant coating/treatment is. The strings then also act toshield the working tip 16.1′, 16.2′.

In order to permit pulling, the pulling means 19, consisting of a nip ofrollers on top of ach other, of which nips there can be several oneafter the other, can be arranged, in the direction of their longitudinalaxis, to be such as that it is possible to support the pulling to theedge strips 16.1, 16.2 being on both edges of the base structure 15. Inthat case, the rollers can be shaped in zones according to the thicknessof the profile being manufactured, so that the main pulling compressionacts on the strips 16.1, 16.2. Such a set of pulling rollers 19 is alsopossible, in which there are two parallel nips for the strips 16.1, 16.2protruding from both edges of the base structure 15. There are alsodiverse possibilities for implementing the pulling 19. Examples of thedimensions of the edge strips 16.1, 16.2 are given a little later.

Some, but of course in no way limiting examples of the possiblematerials for the strips 16.1, 16.2 are a plastic strip in a band form,a metal strip, composite, ceramics, or glass. The fibre orientations inthe longitudinal and transverse directions of composite strips can bearbitrary. In addition, the angles of the fibres can deviate from eachother. The composite forming the edge strips 16.1, 16.2 can haveproperties of extreme heat resistance (an operating temperature of, forexample, 400 C.) compared to the composite of the base structure 15(operating temperature, for example, 200 C.). This can make its priceeven many times that of the composite forming the base structure 15, sothat it is sensible to use it in the wear areas.

The strips 16.1, 16.2 can be treated in such a way that to their surfaceis brought a ceramic surface, a sintered surface, diamond surface, anoble metal surface, chrome surface, or some combination of these.Different kind of nitride, oxide, and carbide surfaces are alsopossible, as are heat-treated surfaces. The treatment or coating canalso be applied to the entire edge-structure part 16.1, 16.2, or to onlythe ‘work point’, i.e., the actual wear-tolerance area 16.1′, 16.2′ incontact with the object being doctored. In itself, the coating or thesurface treatment of the edge strips 16.1, 16.2 is not intended torestrict the basic idea of the invention, but instead various kinds ofcoatings and treatments, which have been able to be made to theedge-band strip 16.1, 16.2 prior to the pultrusion process, will beobvious to one versed in the art. Of course, treatments and coatings canbe made instead of, or along with pre-treatment even after thepultrusion process, if for some reason the situation requires this.

FIGS. 2 a and 2 b show one example of a composite blade 10 according tothe invention, which has been obtained by detaching it from a bladeblank 22. FIG. 2 a shows a cross section of the blade 10 while FIG. 2 bshows a side view of the piece of the blade 10. The blade 10 consists ofa base structure 15 containing several fibre layers as a compositestructure. The base structure 15 is equipped with at least one wear area16.1, 16.2, which is laminated to it. Such a blade 10 can have beenmanufactured in the pultrusion process 20 according to the invention, inwhich the fibres 11 have been pulled through stages characteristic ofthe process, such as, for example, at least an impregnation stage 12 anda curing stage 14.

At least one of the wear areas of the blade 10 have been formed of anindependent edge-structure part 16.1, 16.2, which is attached to thebase structure 15, for example, during the pultrusion process 20according to the invention. An edge-structure part 16.1, 16.2 is nowattached to both edges of the base structure 15, which permits thefibres 11 to be pulled through the pultrusion process 20 without actualpulling fibres. In this embodiment, the edge strips 16.1, 16.2 with thebase structure 15 form a quite sheet-like shape, so that they are flatin the longitudinal axis and in the width direction. Of course, the edgestrip 16.1, 16.2 can be at a small angle relative to the composite basestructure 15.

One example of the total width of a blade 10 according to the inventionis 60-350 mm, such as, for example, 150-250 mm. In that case, the widthof the edge strip 16.1, 16.2 can be 2-100 mm, such as, for example, 5-60mm. The thickness of the material of the base structure 15 of the blade10 can be 0.5-10 mm, such as, for example, 1-5 mm. In that case thethickness of the material of the edge strip 16.1-16.2 can be 0.1-6 mm,such as, for example, 0.2-4 mm. The penetration of the edge strip16.1-16.2 to the base structure 15 can be, for example, 1-90% of thewidth of the base structure 15. From this penetration area, the edgestrip 16.1, 16.2 is surrounded by the fibre layers of the base structure15 on at least one side (asymmetric joint), or even on both sides, whilefrom the other areas it protrudes from the edge of the base structure15, being clearly separate from the actual base structure 15 itself Whendoctoring, the heat due to friction is transferred effectively, forexample, from a metallic edge strip 16.1, 16.2 to the fibre composite15, which effectively conducts the heat away from the work point 16.1′,16.2′ of the blade 10 to elsewhere in the blade 10.

According to one embodiment, bonds 17.1-17.8, or at least some form ofanchoring, can be arranged in the edge strips 16.1, 16.2 of the bladeaccording to the invention. These are intended to ensure the cast jointbetween the edge strips 16.1, 16.2 and the base structure 15. The insetof FIG. 2 b shows a first example of a manner of arranging the bonds17.1-17.8.

The bonds 17.1-17.8 can be arranged, for example, in connection with thecoiling of the edge strips onto a coil 16′, when manufacturing it, oronly once the edge strip 16.1, 16.2 is fed to the pultrusion process 20.If the dimensions/shapes/arrangement of the bonds 17.1-17.8 in the edgestrip 16.1, 16.2 vary, for example, on the basis of the blade blank 22being made at the time, then in that case it is possible to use an edgestrip 16.1, 16.2 of a set dimension in the manufacture of several typesof blade, if its dimensions and properties otherwise permit this. Theanchorages 17.1-17.8 itself can then be made before the strip 16.1, 16.2is fed to the pultrusion process 20, in which case the edge-strip blank16′ can be otherwise already in its final form. In order to create acontinuous and undisturbed pultrusion process, it would appear that anedge strip 16.1, 16.2 that is prefabricated already in its final form,i.e., one that is equipped with bonds 17.1-17.8 is the most advantageousform of implementation. It should be noted that the invention alsorelates to edge-strip blanks 16′ equipped with bonds 17.1-17.8, by whichthe strip 16.1, 16.2 can be led into, for example, the continuouspultrusion process 20, in order to manufacture a blade 10 according tothe invention.

In addition to the bonds 17.1-17.8 ensuring the joint between the edgestrip 16.1, 16.2 and the base structure 15, they also form athree-dimensional space for the impregnating agent 23, whichimpregnating agent 23 the edge strip 16.1, 16.2 being fed to the processcan also be impregnated prior to its being led to the pultrusion die 14′together with the composite 11, 23.

One example of creating the bonds 17.1-17.8 is stamping. Roughening canalso become into question for creating the bonds besides, or in place ofstamping, but a clear 3D formation given to the strip 16.1, 16.2 bystamping will, however, create a better penetration/retention of theimpregnation agent 23 in the strip 16.1, 16.2 while simultaneously alsoforming a real mechanical anchor to ensure the cast joint between theedge structure 16.1, 16.2 and the base structure 15. The use ofroughening by itself may not necessarily achieve sufficientanchoring/penetration space for the impregnation agent/fibres, becausethe thermal expansion of the composite 15 is sufficiently different tothat of, for example, a metallic edge strip 16.1, 16.2. Thus thermalexpansion may cause weakness in the joint, which may result in the bladebreaking up, for example, when in use. If the stamping is performedimmediately prior to the strip 16.1, 16.2 being led to the pultrusionprocess 20, stamping means (not shown) will also form part of thepultrusion process 20.

If the strip 16.1, 16.2 is of composite, for example, it will then bepossible to impregnate it with a polymer material 23. If the strip 16.1,16.2 is dipped in the impregnating agent 23 in stage 12, its surfacewill become impregnated over the desired area. The impregnated area canbe, for example, precisely the area that is cast together with thecomposite base structure 15 in stage 14. In connection with soaking, agreat deal of the impregnating agent 23 will also adhere to the bonds17.1-17.8, where it will remain attached thanks, among other things, toits surface tension and the advantageous shape of the bonds 17.1-17.8.

The bonds 17.1-17.8 can form of symmetrical groups of bonds 18.1-18.3 ata distance from each other. One example of the distance between thegroups is 3-1000 mm, such as, for example 5-300 mm. According to oneembodiment, the bonds 17.1-17.8 belonging to the groups 18.1-18.3 canform an asymmetrical arrangement when examined from one side of thestrip 16.1, 16.2, in which pairs of counter bonds (for example, 17.1,17.5) are on opposite sides of the strip 16.1. Such an arrangement canbe used to increase the strength of the joint between the strip 16.1,16.2 and the base structure 15. In order to group the bonds 17.1-17.8 ata set distance from each other, the stamping machine is programmed tomake them discretely, taking into account the speed of travel of thestrip 16.1, 16.2 in the stamping machine/pultrusion.

According to one embodiment, the groups 18.1-18.3 of bonds 17.1-17.8 canform a star pattern. Other patterns can also be considered. In such astar pattern 18.1-18.3, there are also stamped attachment wings 17.1,17.3, 17.5, 17.7, corresponding to the intercardinal points of thecompass, between four attachment wings 17.2, 17.4, 17.6, 17.8corresponding to the four cardinal points of the compass. The stampingis two-sided, so that it can be carried out alternately on both platesides of the strip 16.1, 16.2. As a result of this, every second stampcan form a concave cup on a side of the strip 16.1, 16.2 and every otherstamp a convex cap. An example of the diameter of the cup/cap is 1-15mm, such as, for example, 2-10 mm. Because in the stamping the edgestructure ‘punches’ part of the edge of the cup and cap, this offers aneven better adhesion/penetration hole for the impregnation agent 23.

As a result of the punching, the impregnation agent 23 brought to oneside of the strip 16.1, 16.2 makes contact with the impregnation agent23 brought to the other side of the strip 16.1, 16.2, through thepunched points. This further reinforces the joint, because from thispoint that is pierced by punching the impregnation agent 23 forms a‘spike’ through the strip 16.1, 16.2. Additional strengthening of thejoint between the strip 16.1, 16.2 and the composite 15 is also providedby the fact that once hardening the impregnation agent 23 that hasadhered already to the actual adhesion cups 17.1-17.8 in stage 12 formsa bump that holds the strip 16.1, 16.2 in its place.

FIG. 3 shows a second example of the implementation of the bonds 25. InFIG. 3, the strip 16.1 is shown when examining it as an axial image. Thebonds 25 now are formed of bends 25 made in the edge of the strip 16.1to be cast into the composite 15.

The bends 25 can be at a distance from each other in the direction ofthe longitudinal axis of the strip 16.1 and they can point alternatelyto opposite sides of the strip 16.1. The length of the bends 25 in thedirection of the longitudinal axis of the strip 16.1 can be, forexample, 10-100 mm and the distance between the bends 10-100 mm. Thebends 25 can follow each other immediately, or there can be an unbentprotection area between them, as in the case shown by FIG. 3.

The angle of a bend 25 relative to the flat-plate basic character of thestrip 16.1 can be 90 degrees, or even greater. In that case, the bendcan be formed using a sharp turn-up, when it will form a hook-shaped‘catch’ that firmly holds the strip 16.1 to the composite base structure15.

Also various wave shapes, (for example, sine waves, saw-shaped, orsquare shaped) can be some examples of the bonds. In general it ispossible to refer to formations, which lead to a deviation from the flatand plate-like basic character of the strip 16.1, 16.2.

The use of a bond-arrangement positioning the edge structure 16.1, 16.2to the composite 15 has been achieved extremely high strength in alldirections, so that the edge strip 16.1, 16.2 is sure to remain securein the composite base structure 15. This permits particularly theembodiment shown in FIGS. 2 a and 2 b. This is important in terms of thedurability of the blades 10, because blades that flex in the directionof the longitudinal axis are very long when handled and are loaded attheir points of use. Thus stresses appear in every direction in theblade 10. By means of the composite 15 and the strip 16.1, 16.2 attachedto it, a blade 10 that is very flexible in the direction of itslongitudinal axis is achieved, as well as the stiffness required in thedirection of the width of the blade, both of which are important inmaintaining a doctor contact over the entire length of the roll beingdoctored.

FIG. 4 shows a second embodiment in order to manufacture a blade 10according to the invention. In this case, the strip 16.1, 16.2 is notattached to the base structure 15 in connection with the continuouspultrusion process 20, instead this takes place as a post-operation. Nowin the pultrusion process 20 only a continuous composite shaped-profilebase structure 15 is made, to which as a method and base structure of ablade 10 the invention also concerns. Now in the die 14′ there areshapes, by means of which a recess 24 or more generally a place for theedge-structure part 16.1, 16.2 is formed in the base structure 15, inboth of its edges. The strip 16.1, 16.2 can be attached to this recess24 after the pultrusion process 20.

The attachment can be performed, for example, in such a way that a strip16.1, 16.2 equipped with bonds 17.1-17.8 is placed in the groove 24formed for it in the edge of the base structure 15, after which thestrip 16.1, 16.2 can be arranged to act as an electric resistance. Anelectric current led to the strip 16.1, 16.2 raises its temperature tothe operating temperature of the matrix agent. This causes the strip16.1, 16.2 to melt onto the composite base structure 15 while at thesame time a strong cast bond is formed between them, which the bonds17.1-17.8 reinforce. In the case of thermoplastic, this can be calledmelting while in the case of thermoset it can be referred to as theresin penetrating into/adhering to the shapes of the strip 16.1, 16.2.In any case, the matrix agent 23 of the composite melts and takes theshape of the possible bond shapes of the strip 16.1, 16.2. When theelectro-melting is terminated, the matrix agent hardens and the resultis that the strip 16.1, 16.2 is firmly cast into the actual basestructure 15. This post-attachment of the strip 16.1, 16.2 to the basestructure 15 brings the advantage of, among other things, eliminatingpossible differences in thermal expansion between the base structure 15and the strip 16.1, 16.2, if both are of a composite material, forexample. According to the embodiment, the equipping of the basestructure 15 with at least one wear area can take place already in thepultrusion process 20 (on-line), or only after it (off-line). It is alsopossible to glue the strip 16.1, 16.2 to the base structure 15.

In the embodiments described above, the base structure 15 of the blade10 has been a shaped profile, which is plate-like, i.e., essentiallywithout corners. Within the context of the invention, the term ‘shapedprofile’ can be understood very widely, so that the base structure 15can also deviate from one that is a flat plate throughout. FIG. 5 showsa second example of an application of a composite base structure 15consisting of a shaped profile. In it, the base structure's 15 edges,from which the edge strips 16.1, 16.2 protrude from the base structure15, are at a selected angle relative to the flat plate-like central partof the base structure 15. The angle a can be, for example, 0-90. Theangle a can be in one edge of the base structure 15, or in both of itsedges. The use of a shaped profile structure of this kind achievesadvantage in, among other things, the control of the travel of the web.

FIGS. 6 a and 6 b show yet another embodiment of the implementation ofthe bonds. In FIG. 6 a, there are opposing claws 28.1, 28.2 in both theedge structure 16.1 and the base structure 15, which ensure that theedge structure 16.1 will remain firmly in the base structure 15, oncethe edge structure 16.1 has been pushed into the deep groove 24 of thebase structure 15. In FIG. 6 a, the claws 28.2 of the base structure 15face into the groove 24. In FIG. 6 b, there are internal shapes 28.3 inthe groove 24, the corresponding of which external shapes can be in theedge structure too. The type of edge structure shown, for example, inFIG. 3 can be applied to this base structure.

It is possible to make blades 10 for several different operatingpositions, from a blade blank 22 manufactured in the manner according tothe invention. Besides the blade 10 being able to be used as a doctoringand cleaning blade in a paper or board machine, it can also be appliedin coating machines/devices, in pulp machines, in printing machines, intissue machines, or in general in applications relating to webformation, papermaking, and closely related fields andfinishing/processing points, in which doctoring is performed for one ormore purposes. The blade 10 can be further used in the aforementionedmachines as a cleaning blade maintaining runnability and the quality ofthe paper, and/or as a servicing blade, in which the surface beingdoctored is serviced (for example, ground/polished) by the blade, inorder to maintain the original state of the roll, or to achieve it. Inthe case of a cleaning blade, undesirable substances that have adheredto the surface of the roll are removed from it. In addition, afibre-reinforced reinforced plastic composite blade 10 equipped with theedge structure 16.1, 16.2 according to the invention is also suitablefor use as a paper-web transfer doctor.

For example, in coating-device applications arranging a wear-resistanttip 16.1′, 16.2′ in the strip 16.1, 16.2 is of great importance. Even asmall amount of wear in the tip 16.1′, 16.2′, which results in a changein the angle of contact between the blade 10 and the surface beingdoctored, will immediately affect the amount of coating remaining on thesurface. The surface can be, for example, a coating roll, or the webbeing coated, depending on the manner of coating. This, in turn, willdirectly affect the quality of the paper being coated. According to theprior art, blades have had to be changed in coating devices at intervalsof even only a few hours. Thus a wear surface that is permanently madein the wear area of the strip 16.1, 16.2 will increase the usefuloperating time of the blade 10, because by using it the amount ofcoating on the roll/web can be made to remain as stable as possible fora long time.

At its simplest, the blade 10 can be detached from the blade blank 22 bycutting off a set length it from a reel 27. The edge-strip structure16.1, 16.2 will then consist of two wearing edges 16.1′, 16.2′ in theblade 10, which permit its use as a reversible blade. When one edge16.1′ of the blade 10 is completely worn out, the blade 10 can bereversed and the other edge 16.2′ used. Once both edges 16.1′, 16.2′have worn out, the blade 10 can surprisingly still be split in themiddle along its longitudinal axis (the broken line in FIG. 2 a) Thiswill provide still two identical blades, the split face of which, i.e.,the composite base structure 15 of the blade 10 forms a work areaintended to be a wearing blade part. Such a blade can be used as anormal doctor blade, for example, in some ‘soft’ roll position, in whichprecisely composite blades are generally favoured.

The use of an edge structure 16.1, 16.2 protruding outside the edge ofthe composite 15, in turn achieves a reduction in the wear of thecomposite base structure 15. Generally too, the edge structure 16.1,16.2 is more resistant to wear than the composite base structure 15.

According to a second embodiment, the blade 10 can be already directlysplit along the broken line shown in FIGS. 2 a and 2 b, in connectionwith detaching from the blade blank 22. The splitting can be performedin such a way as to create a work point of the desired kind. Thusimmediately originally two identic blades is obtained that is equippedwith two different kinds of work areas. One work area will now have astrip while the other work area will be of the base structure 15. Thepossible applications for the use of the blade 10 are surprisinglydiverse.

Retaining elements and/or shapes (not shown), which remain in the gap ofthe blade holder and prevent the blade 10 from dropping out of theholder, can be arranged in ways that are, as such, known, in theopposite edge to the blade's 10 work edge 16.1′, 16.2′ at any time,either in the base structure 15 and/or in the edge part 16.1, 16.2.

It must be understood that the above description and the related figuresare only intended to illustrate the present invention. The invention isthus in no way restricted to only the embodiments disclosed or stated inthe Claims, but many different variations and adaptations of theinvention, which are possible within the scope on the inventive ideadefined in the accompanying Claims, will be obvious to one versed in theart.

1. A blade, which is formed of a composite base structure, to which isfitted at least one wear area and of which blade at least its basestructure is manufactured in a pultrusion process, in which fibres arepulled through at least an impregnation stage and a curing stage,characterized in that the wear area is arranged to form anedge-structure part protruding outside the edge of the base structure.2. The blade according to claim 1, wherein the edge-structure part isfitted to both edges of the base structure.
 3. The blade according toclaim 1, wherein the bonds are arranged in the edge-structure parts, inorder to ensure the joint between the edge-structure parts and the basestructure.
 4. The blade according to claim 1, wherein the bonds formgroups, the bonds of which groups are arranged in a symmetrical pattern,in order to increase the strength of the joint between theedge-structure part and the base structure.
 5. The blade according toclaim 2, wherein the bonds are arranged in the edge-structure parts, inorder to ensure the joint between the edge-structure parts and the basestructure.
 6. The blade according to claim 2, wherein the bonds formgroups, the bonds of which groups are arranged in a symmetrical pattern,in order to increase the strength of the joint between theedge-structure part and the base structure.
 7. The blade according toclaim 3, wherein the bonds form groups, the bonds of which groups arearranged in a symmetrical pattern, in order to increase the strength ofthe joint between the edge-structure part and the base structure.